1. Technical field
This invention relates to the field of aircraft ground servicing, specifically, to the provision of electrical, fluidic, and gaseous inputs to fixed and rotary wing aircraft at the airfield and on the flightline. An aircraft on the ground whose engine is not functioning requires a number of services to determine whether the aircraft is in a condition to fly or taxi. These services include: electrical power, hydraulic power, engine-start capability (bleed-air), air conditioning or heating of the aircraft""s interior, and nitrogen to inflate struts and operate power tools.
2. Background Art
Aircraft Ground Power Units (AGPUs) have been in existence for nearly as long as piston- and turbine-powered aircraft. The shrinking of the defense budget, combined with the increasing projection of U.S. military power throughout the world, requires the armed forces to do more with less equipment and fewer personnel. Thus labor-intensive tasks are increasingly burdensome to today""s leaner military. Thus there is concern that employing older flightline equipment, such as the prior art AGPUs, is incompatible with present-day military manpower and logistics.
The prior art has substantial limitations. Currently, a separate AGPU is required for each requirement (hydraulics, conditioned air, nitrogen, electricity, air start, etc.). Each AGPU must be towed into place adjacent the aircraft to be serviced. Towing each separate AGPU takes time, tying up equipment, the tow vehicle itself, and the people required to operate both the power unit and the tow vehicle. Wartime conditions make servicing each aircraft more difficult.
No currently available AGPU provides all the outputs necessary to service a wide variety of aircraft. Thus each flightline must maintain a multiplicity of separate AGPUs for each aircraft type. Further because no currently available AGPU is self-powered, each must be manually connected to a tow vehicle and brought adjacent to the aircraft to be serviced. For example, the U.S. Army currently uses an AGPU (NSN 1730-01-144-1897, produced by Engineered Systems, Inc.; see Army Technical Manual TN 55-1730-229-12 or Air Force Technical Order TO 35C2-3-473-1) that is very heavy, hard to move (because it is not self-propelled), and that does not provide the voltages and frequencies required by all aircraft the Any employs.
A prior attempt to sol the logistics problems associated with multiple, towed, AGPUs is disclosed in U.S. Pat. No. 4,101,100 to Smith et al. Smith et al. discloses a system of servicing islands that furnish compressed air, electricity, and conditioned air from a common source. While Smith et al. discloses how to supply a plurality of servicing inputs to an aircraft, the aircraft itself must be towed to the island.
Thus Smith et al. fails to solve the problem addressed by the present invention for at least three reasons. First, a tow vehicle is still required to bring the aircraft to the service island. If multiple aircraft must be moved into position simultaneously for servicing, as Smith et al. suggests, then multiple tow vehicles are required. Thus Smith et al. teaches away from the present invention, which eliminates multiple towing. Second, not all aircraft can be towed. Rotary-wing aircraft (e.g., helicopters) may not have wheels and therefore cannot be towed. It is therefore not clear how helicopters could utilize the island disclosed by Smith et al. In contrast, the present invention teaches how to service all aircraft (both fixed and rotary-wing) by bringing a unitary servicing apparatus to the aircraft. Third, the present invention discloses means for aircraft servicing in forward-deployed areas of the world, encompassing makeshift airfields over unimproved terrain. Smith et al requires installation into an airfield, even if the installation be temporary rather than permanent. The present invention, on the other hand, requires no installation. It is inherently portable and thus best addresses rapid deployment to remote, unimproved regions.
Prior-art AGPUs also require manual configuration and monitoring each time they are employed to service an aircraft. That is, each AGPU must be manually set up each time it services an aircraftxe2x80x94even if the same type of aircraft is being serviced repetitively.
It is therefore an object of the present invention to provide an apparatus that overcomes the deficiencies of the prior art in ground servicing of aircraft.
It is a further object of the present invention to provide a single, self-powered unit that combines all the components necessary to service a variety of aircraft without requiring power from the aircraft itself.
It is another object of this invention to automate the process of aircraft servicing.
It is a still further object of this invention to control through a computer the components necessary to service an aircraft.
It is yet a further object of this invention to provide computer programs that recognize different aircraft and automatically configure all of the components necessary to service a particular aircraft.
It is still another object of this invention to provide a mountable and demountable air cycle machine for producing conditioned air for servicing an aircraft.
It is yet still a further object of this invention to provide a valve to divert bleed air from a subsystem power unit to either an air cycle machine, a buddy start system, or a deicing system.
An additional object of the present invention is to provide at least one access point on an AGPU from which to make all connections to the aircraft to be serviced.
A further additional object of the present invention is to achieve operation over varying terrain to permit forward deployment in remote areas.
The present invention achieves these and other objects through a single, self-powered, self-moving vehicle on which is detachably mounted a self-contained, self-powered,, and computer-controlled service unit that supplies all inputs required to service an aircraft. The present invention eliminates separate tow vehicles and co-locates all of the aircraft servicing outputs in a single unit.
The present invention reduces the number of servicing units required on the flightline. For example, to start the Comanche helicopter requires 30-35 kw of 270 volt DC power, about 40 lbs./minute of cooling air, about 12 gals./minute hydraulic power at 3,000 psi,, and about 40 lbs./minute bleed-air. So, to service the Comanche, one or more AGPUs must have mounted on them units that provide each of these services. The Apache Longbow helicopter, however, requires about 75 kw of 120 volts, 400 Hz AC power and about 100 w of 28 volt DC power. So, to service the Apache, the one or more AGPUs require different generators than to service the Comanche. (Cooling requirements are approximately the same for both aircraft.) Given the plethora of aircraft in the military inventory, the present invention eliminates maintaining a large number of AGPUs, one for each type of aircraft.
A computer inside the enclosed service unit of the present invention monitors the components that service an aircraft through software programs and an operator interface. The type of aircraft is chosen from a menu-driven display. The computer responds to the operator""s selections and rapidly configures the AGPU of the present invention to supply the correct servicing outputs in the correct quantities for that particular aircraft. This simple method of configuring contrasts with the prior-art devices that require the operator to manually configure each separate (and separately towed) servicing unit. Configuring the prior-art servicing units can require an operator either to page through extensive operation manuals or to be trained extensively to apply specialized knowledge. At best, the prior-art device depends upon a highly skilled operator; at worst, it may fail for lack of an experienced operator.
Nothing in the prior art teaches or suggests this aspect of the present invention. In the prior art, there is no built-in database for servicing aircraft. The data exist in separate servicing manuals for each type of aircraft and, perhaps, in the operator""s memory. Furthermore, once the operator decides upon the parameters of the servicing outputs to supply the aircraft, he must manually configure the unit by rotating knobs, throwing switches, reading dials and gauges to successfully service the aircraft. The present invention reduces the labor required and minimizes the possibility of operator error.
In the preferred embodiment of the present invention, an air cycle machine is mounted atop the enclosure, and its input is coupled, through the enclosure, to the bleed air output of the prime mover. The air cycle machine thus benefits from the self-containment and self-mobility of the AGPU of the present invention. In the prior art, the air cycle machine must be separately towed into position. Alternatively, in the present invention the air cycle machine can be removed and made independent of the AGPU. At the point where the air cycle machine would otherwise directly connect, a duct may be connected to the bleed air exit from the AGPU. This duct can be coupled to an air cycle machine, a deicing system, or a buddy-start system, any of which may be located remotely from the AGPU.
Rough terrain presents a significant obstacle to the towed units of the prior art.
Rotary-wing aircraft (e.g., helicopters) and certain fixed-wing aircraft (e.g., Harrier jets and V-22 Osprey) operate in forward deployment, and they must be serviced by AGPUs. The prior-art units would be wholly ineffective in such environments. This deficiency is overcome by the present invention.
Briefly stated, an AGPU is a mobile vehicle, preferably self-propelled, on which is mounted an enclosure. Within the enclosure are a number of subsystems, each of which provides a service required by a stationary aircraft for servicing and diagnostic testing prior to flight. Such services include electrical power, hydraulic power, engine-start capability (bleed-air), conditioned air (hot or cold) for the aircraft""s equipment recesses or interior, and nitrogen to inflate struts and operate power tools. The control, status, configuration, and automation of all of the subsystems contained within the enclosure are consolidated under computer control. The enclosure and the subsystems contained therein can be readily mounted on and dismounted from the vehicle.
According to an embodiment of the invention, apparatus for servicing an aircraft comprises: a self-propelled vehicle; a service unit detachably mounted to the vehicle; the service unit being controllable by a computer; and the service unit being effective for providing a plurality of outputs.
According to a feature of the invention, a method for servicing an aircraft, comprises the steps of: installing at least one program in at least one computer; storing an aircraft servicing database in the at least one computer; configuring a service unit according to the database to service a chosen aircraft; and applying the service unit to service the chosen aircraft as directed by the at least one program.
According to another feature of the invention, apparatus for servicing an aircraft comprises: at least one program installed in at least one computer; an aircraft servicing database stored in the at least one computer; a service unit configured according to the database to service a chosen aircraft in response to instructions in the at least one program; and the service unit being mounted on a self-propelled vehicle.
These and many other objects and advantages of the present invention will be readily apparent to one skilled in the pertinent art from the following detailed description of a preferred embodiment of the invention and the related drawings, in which like reference numerals designate the same elements.